The data rate at which a wireless device transmits may depend on the wireless environment in which the device is transmitting. The wireless environment may be affected by such factors as interference, packet collisions, reflections, etc. A wireless device may attempt to select an optimal data rate for a given environment using a data rate selection algorithm.
In the IEEE 802.11 family of specifications, a wireless device initiates transmission at the highest possible data rate. If the wireless device receives an acknowledgement (ACK) from a receiving device, it is assumed that the wireless environment can support the highest data rate and further transmissions occur with this (highest) date rate. Otherwise the data rate is lowered in a step-wise fashion until an ACK is obtained. Such a strategy may waste bandwidth. Furthermore, this strategy can lead to successive packet failures, which may cause TCP timeouts and associated decreases in link throughput.